Difference between call signature and function type

Question

I\'m trying to understand why we have different syntax for call signatures and for function types. Consider the following code:

interface MyInterface {
   //         


        

Answer 1

They are exactly the same.

why do we need two different yet so similar ways to write the same thing in typescript

The (x:number, y:number)=>number signature is useful as a property annotation :

interface MyInterface {
    (x:number, y:string):string;   
    someProperty: (x:number, y:number)=>number;
}

Which is similar to your:

var myTwo : (x:number, y:number)=>number

Just a shorthand for a verbose :

var myTwo : {(x:number, y:number):number}

So you can see the simplicity of ()=>.

Also

One thing to note is that a function signature allows overloading:

var myTwo : {
    (x:number, y:number):number;
    (x:number):string;
}

Which is not supported for a property annotation.